I recently bought a black knight butterfly bush. It is very tiny, only about 10" tall. My question is should I plant it outside now? I was hoping to grow it in a pot out in my greenhouse till it got bigger. I'm afraid it will get lost because of its small size if I plant it directly into the ground. Any thoughts/ideas of what would be best would be much appreciated.

They're pretty fast growing... Even seedlings!

Last winter I noticed a couple of buddleia seedlings growing in a cuttings bed...
I left them alone long enough to see flowers (a couple months) they started to take up too much space and I dug them out, added to burn pile.

When planted in moist soils, they tend to invasiveness... If you live near any streams, you might want to re-think...

https://www.finegardening.com/....

And, If you are in a dry hostile environment, they may not grow at all.

Give it a big hole and a good marker, mulch around it.
How is your winter?
I have lost plants to hastily sticking them in the ground but without good prep and marking.

I'd hold it in the greenhouse. I think it's too late for it to establish roots in the ground outside.

Thank you guys for your opinions. I certainly don't live near any water sources. I think I would really risk losing it if I planted it in the ground now. Our winter can be Rouge. Lots of snow and freezing temps.. Or very dry with killer winds and freezing. I think Zoe has the best idea for keeping it alive. I had a black knight a few years ago, but it died. I have a white butterfly bush growing in the front yard so I know they will grow out here.

Not because I'm psychic; I know that terrain. Barren, brutal and yes, killer winds. 😬

Hi Colleen @Agoo

I agree with Zoë @NMoasis, since you have a greenhouse it would be best there over winter while it's small and not established.

I don't know how your white butterfly bush behaves for you. We had 'White Profusion' for decades, and we have had other cultivars but not 'Black Knight'.

Here in zone 6a they were usually killed to the ground in the "normal" winters (some sub-zero in °F). They regrew from below ground. In the occasional global-warming "zone 7+" winters when temperatures did not drop below about 10°F the entire top usually survived and they became woody.

This never lasted enough years to become the shrubby trees like one I saw in Tennessee, and another in Georgia. Here, they reached as high as 7' and almost as wide. Last winter was especially harsh because of a sudden drop to 6°F without adequate time to acclimate. Only one survived. It began as a seedling.

I did have seedlings from several of the cultivars over the years but I wouldn't call them invasive. Their favorite places to volunteer were actually in some of the worst spots. They were especially frequent in limestone-y spots like our driveway and a bed near a retaining wall which has some limestone gravel backfill. Some seedlings actually volunteered and grew in the crevices of the retaining wall blocks!

The database shows 52 members have 'Black Knight'. There are photos from gardens in a wide range of climates including some probably colder and some drier than your 5b in NM, Colleen. So I expect it will do well when established.

Pat